It is proposed to investigate permeability characteristics and carbohydrate transport in the epithelia of the seminiferous tubule and caput epididymis using micropuncture and microperfusion techniques. An understanding of the permeability (blood testis and blood epididymal barriers) and carbohydrate transport in these epithelia is essential to comprehend how the testis and epididymis maintains a suitable microenvironment for spermatogenesis and epididymal sperm maturation; it should also facilitate a search for a potential male contraceptive agent. Except for the previous studies of the co-principal investigators there is very little information of this nature on the testis and epididymis. This proposal is part of a long term study of the physiology of the SNT and epididymis in our laboratory.